The Treaty of Commerce and Navigation was signed on March 25, 1940 between representatives of Iran

Iran

Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

 and the Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

. This accord helped to reinforce the tenets of the Treaty of Establishment, Commerce and Navigation

Treaty of Establishment, Commerce and Navigation

The Treaty of Establishment, Commerce and Navigation was signed on August 25, 1935 between representatives of Iran and the Soviet Union. This accord helped to reinforce the tenets of the Russo-Persian Treaty of Friendship...

. Based on the terms of the treaty, both signatories agreed to reinforce the 10-mile fishing limit for all commercial vessels in the Caspian Sea

Caspian Sea

The Caspian Sea is the largest enclosed body of water on Earth by area, variously classed as the world's largest lake or a full-fledged sea. The sea has a surface area of and a volume of...

. Moreover, both signatories agreed that only Iranian and Russian commercial vessels were permitted to fish beyond the 10-mile nautical limit. The treaty did not include any clauses regarding the issue of seabed mining.

Source

• Mehdiyoun, Kamyar. "Ownership of Oil and Gas Resources in the Caspian Sea." The American Journal of International Law. Vol. 94, No. 1 (January 2000), pp. 179-189.